This invention relates generally to linear roller bearings and, more particularly, to linear roller bearings that may be used in coaxial, tubular arrangements that transmit torque from one tube to a coaxial tube while allowing free relative axial movement of the coaxial tubes.
With current linear roller bearing practice, parallel rollers may be retained in a crosswise orientation in elongated bearing cages, between inner and outer coaxial tubes, such that one tube can transmit torque to the other tube while being free to move axially with respect to the other. However, in applications where different magnitude loads and speeds result in high static friction, performance of such linear roller bearings may be unacceptable. The bearings can bind with high loads and the rollers can slide with low loads, such that the bearing cages may travel axially at different rates, resulting in bearing cages being located at different axial positions along the coaxial tubes. This misalignment of the bearing cages prevents the linear roller bearings from operating effectively to transmit torque and to facilitate free relative axial movement of the coaxial tubes.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
In one aspect of the invention, this is accomplished by providing a linear roller bearing for guiding axial movement of an inner tubular member with respect to a coaxial outer tubular member. The linear roller bearing comprises at least two pairs of elongated inner and outer linear bearing races, for extending axially with respect to an axis of coaxial tubular members and to be mounted on the inner and outer coaxial tubular members, respectively, such that the inner linear bearing race of each pair is radially aligned with and radially inward of the respective outer linear bearing race. A plurality of parallel rollers is positioned between each pair of inner and outer linear bearing races for rolling movement along the length of the inner and outer linear bearing races. The rollers between each pair of inner and outer linear bearing races are retained within a bearing cage extending laterally to form a mechanical interlock with an adjacent bearing cage to limit relative axial movement of the adjacent bearing cage.
In other aspects of the invention, this is accomplished by providing a coaxial tubular linear roller bearing arrangement and by providing a bearing cage for use in a coaxial tubular linear roller bearing arrangement.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.